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Water PollutionMiller Ch. 19
APES
Any chemical, biological and physical change in water quality that has a harmful effect on living organisms or makes it unusable for agriculture
The massive quantity of pollutants produced by > 6 billion humans, their machines, plants, animals
The limited supply of fresh liquid water into which most water-destined pollutants are discharged
The growing number of ‘technological pollutants’ released into the environment, i.e. manufactured synthetic materials
Water Pollution
•Point sources (e.g., factories, sewage treatment plants, mines, oil wells, oil tankers)
•Nonpoint sources (e.g., acid deposition, substances picked up in runoff, seepage into groundwater)•Agriculture is largest source of water pollution in the U.S. (64% of pollutants into streams and 57% of pollutants entering lakes)
Sources of Pollution
Disease-causing Agents – pathogensOxygen Demanding Agents – organic
waste: manureWater-soluble Inorganic Chemicals –
acids, toxic metals Inorganic Plant Nutrients – nitrogen and
phosphorusOrganic Chemicals – oil, pesticides,
detergentsSediment or Suspended Material –
erosion, soilWater-soluble Radioactive Isotopes –
radon uraniumHeat – electric and nuclear power plantsGenetic Pollution
Types of Pollution
Disease symptoms usually are diarrhea and /or vomiting
Waterborne Bacteria
Escherichia coli Vibrio sp.
Waterborne Protozoans
Guardia sp.**P. Darken
• Disease symptoms are usually diarrhea and/or vomiting.
Waterborne Human Viruses
Hepatitis A virus Hepatitis E virus
Norwalk virus* Rotavirus*
Waterborne Parasites
Disease-causing Agents - PathogensOxygen Demanding AgentsWater-soluble Inorganic ChemicalsInorganic Plant NutrientsOrganic ChemicalsSediment or Suspended MaterialWater-soluble Radioactive IsotopesHeatGenetic Pollution
Types and Sources of Pollution
BOD: Oxygen is removed from water when organic matter is consumed by bacteria.
Low oxygen conditions may kill fish and other organisms.
Sources of organic matter Natural inputs-- bogs, swamps, leaf fall, and
vegetation aligning waterways. Human inputs-- pulp and paper mills, meat-
packing plants, food processing industries, and wastewater treatment plants.
Nonpoint inputs-- runoff from urban areas, agricultural areas, and feedlots.
Biological Oxygen Demand (BOD)
BOD Effects on Water Quality
All streams have some capability to degrade organic waste. Problems occur when stream is overloaded with biochemical oxygen-demanding waste.
Disease-causing Agents - PathogensOxygen Demanding AgentsWater-soluble Inorganic Chemicals
Inorganic Plant NutrientsOrganic ChemicalsSediment or Suspended MaterialWater-soluble Radioactive IsotopesHeatGenetic Pollution
Types and Sources of Pollution
Metallic elements having a density greater than 5 g/cm3
Most are extremely toxicWater solubleReadily absorbed into plant or
animal tissueBiomagnification
Combine with biomoleculesProteinsNucleic acids
Heavy Metals
Natural Redistributed by geologic and biologic cycles
IndustrialBurning of fossil fuelsEnvironmental pollution
Sources of Heavy Metals
Broad term used to describe several ways that acids fall out of the atmosphere
Acid Rain
Wet deposition refers to acidic rain, fog, and snow.
Dry deposition refers to acidic gases and particles.
Wet and Dry Acid Rain
Sulfur dioxide (SO2) and nitrogen oxides (NOx)
are the primary causes of acid rain.
In the US, about 2/3 of all SO2 and 1/4 of all NOx
comes from electric power generation that relies on burning fossil fuels like coal.
Causes of Acid Rain
Gases react in the atmosphere with water, oxygen, and other chemicals to form a mild solution of sulfuric acid and nitric acid.
Formation of Acid Rain
Acid rain primarily affects sensitive bodies of water, which are located in watersheds whose soils have a limited “buffering capacity”
Lakes and streams become acidic when the water itself and its surrounding soil cannot buffer the acid rain enough to neutralize it
Some lakes now have a pH value of less than 5
Buffering Capacity
Generally, the young of most species are more sensitive to environmental conditions than adults
At pH 5, most fish eggs cannot hatch
At lower pH levels, some adult fish die
Some acid lakes have no fish
Effects on Wildlife
Disease-causing Agents - PathogensOxygen Demanding AgentsWater-soluble Inorganic ChemicalsInorganic Plant NutrientsOrganic ChemicalsSediment or Suspended MaterialWater-soluble Radioactive IsotopesHeatGenetic Pollution
Types and Sources of Pollution
Selected Pollutants: NutrientsPhosphorus and nitrogen are the major concernsSources:• Human, animal (e.g., Hog Farms), and industrial waste • Storm water• Soil erosion • Excessive use of fertilizers for crops, lawns, and home
gardens
Selected Pollutants: Nutrients
Eutrophication is characterized by rapid increase in plant life. An example is the algae bloom shown here.• Algae blooms block sunlight so
plants below die. • Decomposition of dead plants
consumes oxygen. • Low oxygen conditions may kill
fish etc. • Aesthetics (color, clarity, smell)
High nutrient concentrations can cause Eutrophication (“well-fed” in Greek) of water bodies
Disease-causing Agents - PathogensOxygen Demanding AgentsWater-soluble Inorganic ChemicalsInorganic Plant NutrientsOrganic ChemicalsSediment or Suspended MaterialWater-soluble Radioactive IsotopesHeatGenetic Pollution
Types and Sources of Pollution
Concentrations increase at increasing levels in the food chain – PCBs, DDT, etc.
Biological Magnification
Degradable: That can be chemically decomposed: decomposable plastic wastes
Photodegradable: that the product is decomposed (broken down) by exposure to light
Biodegradable: Capable of being decomposed by biological agents, especially bacteria: a biodegradable detergent
Degradable/Biodegradable
Disease-causing Agents - PathogensOxygen Demanding AgentsWater-soluble Inorganic ChemicalsInorganic Plant NutrientsOrganic ChemicalsSediment or Suspended Material
Water-soluble Radioactive IsotopesHeatGenetic Pollution
Types and Sources of Pollution
Erosion
Sediment (clay, silt) is the #1 source of water pollution. Bare soil easily washes into storm drains and streams, clouding the water and suffocating aquatic life.
• Never leave soil exposed! Place straw over newly seeded areas.
• Cover your garden during winter months.• Sod, seed, grow plants, or build terraces on slopes.• Rock gardens can also be effective for slowing the flow
of water and minimizing erosion.
Effects of Sediment Loading
• Destruction of spawning beds• Adsorption and transport of other pollutants• Reduced light penetration, aquatic
vegetation• Greater nutrients loadings, oxygen demand• Interference with navigation, flood control,
recreation, industry
Disease-causing Agents - PathogensOxygen Demanding AgentsWater-soluble Inorganic ChemicalsInorganic Plant NutrientsOrganic ChemicalsSediment or Suspended MaterialWater-soluble Radioactive Isotopes
HeatGenetic Pollution
Types and Sources of Pollution
Disease-causing Agents - PathogensOxygen Demanding AgentsWater-soluble Inorganic ChemicalsInorganic Plant NutrientsOrganic ChemicalsSediment or Suspended MaterialWater-soluble Radioactive IsotopesHeatGenetic Pollution
Types and Sources of Pollution
Industrial Water Pollution• Thermal Pollution occurs when water is
withdrawn, used for cooling purposes, and then heated water is returned to its original source
• An increase in temperature, even a few degrees, may significantly alter some aquatic ecosystems
Disease-causing Agents - PathogensOxygen Demanding AgentsWater-soluble Inorganic ChemicalsInorganic Plant NutrientsOrganic ChemicalsSediment or Suspended MaterialWater-soluble Radioactive IsotopesHeatGenetic Pollution
Types and Sources of Pollution
Dense mats alter water qualityraising pHdecreasing oxygen under the matsincreasing temperaturestagnant watergood breeding grounds for mosquitoes
Hydrilla will grow with less light and fewer
nutrients, and can out compete other native plants
Fish populations are negatively affected if hydrilla exceeds 30-40% coverage of the lake
Hydrilla: Non-native Aquatic Plant
Flowing water can recover rapidly by dilution and decayPollution of Streams and Lakes
Accelerated results with human input of nutrients to a lake
Eutrophication
Coastal waters especially are highly affected by pollution because they are:Heavily usedClose to sources of pollutionShallow-water bodies Not as well circulated as the open
oceanCoastal pollution is made up of ocean pollution and ocean debris
Pollution in Coastal Waters
Petroleum (oil)Sewage sludgeDDT and PCBsMercuryPoint source: clearly discernable in terms
of origin (municipal sewage outfall, oil tanker spills, offshore oil well blowouts)
Non-point-source pollution: ill-defined or diffused sources, runoff (harbors and marinas, TBT, powerboat pollution, invasive species, agriculture, forestry, urban runoff, ocean debris, air pollution, noise pollution, dredging
Main Types of Ocean Pollution
Oil spills can be caused by:Tanker
accidentsIntentional
dumpingDrilling/
pumping operations
Ocean Pollution: Petroleum
bss.sfsu.edu/ehines/geog600/ Freshwater%20and%20ocean%20Pollution.ppt
•Volatile Organic Compounds immediately kill many of the aquatic organisms (especially plankton and larvae) and contaminate fish
•Floating oil coats birds and ocean mammal; destroys natural insulation and buoyancy and causes deaths
•Heavy oil sinks to ocean bottom and washes into estuaries where it contaminates crabs, oysters, mussels, clams, etc.
•Oil slicks on beaches harm intertidal life and cause economic losses to tourism and fishing industries
Effects of Oil Spills
When oil washes up at a beach, it can negatively affect the ocean environment
Oil can coat ocean organisms and render their insulating fur or feathers useless
Ocean Pollution: Petroleum
Oil on the beach from the Exxon Valdez oil spill, Alaska
Petroleum is biodegradable
Many pollution experts consider oil to be among the least damaging ocean pollutants
Data from the 1989 Exxon Valdez oil spill shows the recovery of key organisms
Ocean Pollution: Petroleum
Various processes act to break up and degrade oil in the ocean environment
Ocean Pollution: Petroleum
Ocean Pollution: Point SourceAre clearly
discernible in terms of origin
Originate from municipal and industrial facilities
Bypasses and overflows from municipal sewage systems
Oil tanker spills and offshore oil well blowouts
Non-point-source pollution comes from material washed down storm drains as “poison runoff”
Includes fertilizers, pesticides, road oil, and trash
Ocean Pollution: Non-Point Source
Plastic:Either does not
biodegrade or not in human time…
FloatsHas high
strengthIs ingested by
and entangles ocean animals
Plastic in the Ocean Environment
•Greater threat to humans than much of more visible surface water pollution
•Much groundwater renewed slowly, such that pollution lingers for long time
•Crude estimates indicate that up to 25% of usable groundwater in the U.S. contaminated
•Extremely difficult to clean up contaminated groundwater; prevention more effective
•Main approach: pump groundwater to surface, purifying water, and returning to aquifer; costs high
Groundwater Pollution
bss.sfsu.edu/ehines/geog600/ Freshwater%20and%20ocean%20Pollution.ppt
75% of 175,000 known waste disposal sites in US may be producing hazardous subsurface plumes (contaminated regions of the subsurface)
Groundwater Pollution
• Salt Water Intrusion
• Extensive pumping in coastal areas can cause salt water to rise into wells, forming a cone of ascension
•Much of the world's drinking water is contaminated and poses serious health threats
•Most drinking water is purified by storage in reservoir (suspended matter settles), and treated by sand filters, activated charcoal, and addition of chlorine
•U.S. Safe Drinking Water Act of 1974 requires EPA to establish national drinking water standards
•Many using bottled water and home filters; bottled water is often more contaminated than tap water
Drinking Water Quality
Water Quality Standards
• The EPA (Environmental Protection Agency) sets Maximum Contaminant Levels (MCLs) for drinking water
• There are standards for numerous contaminants, two of which cause an immediate health threat if exceeded• Coli form bacteria -because they may indicate presence
of disease causing organisms• Nitrate - can cause ‘blue baby syndrome”—nitrate
reacts with blood and blood can’t carry as much oxygen
Municipal Water Purification Plant
Sewage or wastewater is composed of sewage or wastewater from:Domestic used water and toilet
wastesRainwaterIndustrial effluent (Toxic industrial water
is pretreated)Livestock wastes
** Microbes degrade organic compounds** Elimination of pathogens occurs
Sewage or Wastewater Treatment
Wastewater Treatment Types of treatment systems include: Septic
Tanks or Wastewater Treatment Plants (WWTPs).•Septic Tanks typically treat small volumes of waste (e.g., from a single household, small commercial/industrial)
•WWTPs typically treat larger volumes of municipal or industrial waste.
Septic Tanks• Approx. 22 million systems in operation ( 30% of US population)• Suitability determined by soil type, depth to water table, depth to
bedrock and topography• Commonly fail due to poor soil drainage• Potential contaminants: bacteria, heavy metals, nutrients,
synthetic organic chemicals (e.g. benzene)
Wastewater or sewage treatment is a multi step process:
1. Primary Treatment (Physical Process) Removal of large objects using grates and
screensSettling to remove suspended solids (primary
sludge) flocculating chemicals are added to enhance
sedimentation
Sewage Treatment
2. Secondary Treatment (Microbial Process) Supernatant or primary effluent contains
high levels of dissolved organic load (Biological Oxygen Demand)
Aeration to stimulate aerobic degradation
activated sludge reactor trickling filter reactor
Sewage Treatment
bacteria degrade organiccarbon to CO2
• Sludges from the primary and secondary treatment settling tanks are pumped into an anaerobic digester
• Sludges contain cellulose, proteins, lipid and other insoluble polymers
• Anaerobic bacteria digest the sludge to methane and carbon dioxide
Anaerobic Digestion of Sludge
Pathogen Removal by Activated SludgeMore than 90% of E. Coli. and Salmonella
are destroyedBacteria are removed by inactivation,
grazing by ciliated protozoa, and adsorption to sludge solids
Viruses are removed mainly by adsorption process
Sewage Treatment
3. Tertiary Treatment (Physicochemical Process)
Precipitation Filtration Chlorination Treated water is discharged to waterways Used for irrigation
Sewage Treatment
expensive process, sharply reduces inorganic nutrients (PO4, NO3)
The State of South Dakota has a useful generic wastewater treatment plant tour on the web: http://www.state.sd.us/denr/DES/Surfacewater/virtual.htm
The City of Camarillo, CA has a nice and clear virtual tour of their secondary treatment plant: http://www.ci.camarillo.ca.us/csd/tour.html
Wastewater Virtual Tours
The Clean Water Act is a 1977 amendment to the Federal Water Pollution Control Act of 1972Set the basic structure for regulating discharges of
pollutants in the USThe law gave EPA the authority to set water
quality standards for industry and for all contaminants in surface waters
The CWA makes it unlawful for any person to discharge any pollutant from a point source into navigable waters unless a permit (NPDES) is obtained
The amounts and types of pollutants than can be discharged or allowed to run in to waters from watersheds are regulated
Clean Water Act
The Safe Drinking Water Act (1974) was established to protect the quality of drinking water in the U.S
This law focuses on all waters actually or potentially designed for drinking use, whether from above ground or underground sources
Safe Drinking Water Act
Current Law Regulating Ocean Dumping
• The only substance that is illegal to dump anywhere in the ocean is plastic